The goal and vision for the SmartGrass project is to optimize N use in grass swards for both seed and silage production. In order to achieve this goal two overall issues will be addressed in the project: (i) development of sensor technology to recognize spatial patterns of crop growth in the field, and (ii) improving the understanding of optimized N application both in pure grass for seed and in grass-clover mixtures for silage. Benefits in relation to both enhanced yield and reduced environmental impact are therefore expected. To implement the project results in real-life farming practices, the project will: develop a spreader for precision application of mineral N fertilizers; develop a grass-clover module for the MarkOnline decision support system which aids farmers in planning the application of both slurry and mineral N fertilizers; and document the nitrate leaching effect of applied N fertilizer on the clover-grass sward in order to use temporary grasslands as an instrument in Danish N regulation.